Same issue here… I have a Triumph Street Triple with a QuadLock and have gone through 2 trips to the Apple store for replacement of the back camera that started to have focus issues after a few rides. On my last visit to the store they mentioned about this being common on motorcycles!
At least my iPhone11 is still under warranty. Just installed the vibration dampener from QuadLock and we will see how it goes (better test before my warranty expires)… I'll report once I have some answers.